I liked it and thought it was a clever idea. I was skeptical at the beggining because it could be used badly and force you grinding, but it actually was very well balanced. I really liked the idea of upgrading potions, that was a very interesting and clever idea! I do miss earning certain upgrades through minigames, just like you earned the quiver and bomb upgrades. It made you feel happy each time you manage to get one of those upgrades through sidequests or minigames. I did missed that feeling here. I do believe they can elaborare upon it in future games, although I hope they don't make it tedious or force you to grind. One thing I didn't like however, was to get the textbox message explaining you the treasure or bug you collected. The game says it only once, but when you reser the game it resets this feature. It can be annoying at times. Other than that, I actually like to upgrade my items. And it is interesting to denote that its entirely optional, so its more of a very good extra.